1. Field of the Invention
The present invention relates to an apparatus for improving soft ground, which is used in civil engineering works, and more particularly to an apparatus for improving soft ground, in which composite slurry including cement is introduced in an injection rod inserted in the ground and is vigorously discharged from the injection rod by air under a high pressure to cause a hardening agent to easily and evenly infiltrate the soil, thereby improving the soft ground.
2. Description of the Prior Art
In general, a method of improving soft ground is extensively known in the art, in which a monitor inserted in a bore formed in the ground is rotated and retracted upward while discharging a liquid-phase hardening agent, such as cement milk, into the bore, thereby providing a pile-shaped solid body in the bore of the ground.
According to the above-mentioned conventional method of improving the soft ground, because properties of the ground are uneven, an infiltrating region of the hardening agent does not have a uniform shape, as shown in FIG. 7.
In the conventional method of improving the soft ground, an injection rod 5 is inserted into the ground, and water and air, or cement slurry and air, which are pressurized under a predetermined pressure, are horizontally discharged from nozzles 2 and 3, as shown in FIG. 8. For this reason, when the improved construction is undertaken in the soft layer of the ground, a discharging distance of the water and air, or cement slurry and air cannot be controlled, thereby causing an infiltrating range of the liquid or slurry to be excessively enlarged, or causing the liquid or slurry to rise along the soft layer. In addition to this, excessive slime is generated from the soft layer, higher costs are incurred due to excessive charging of the material. Furthermore, when the improved construction is undertaken in a clay layer, a compressive strength of the resulting solid body is lowered.
In the improved construction shown in FIG. 8, the liquid and slurry are discharged from the nozzles 2 and 3 such that the discharging direction of the liquid and slurry defines the right angle with respect to the direction of the liquid and slurry being introduced into the injection rod 5. Accordingly, since a pressure of the liquid and slurry is lowered at the inflection point, the efficiency of the improved construction is deteriorated.